A light source device, such as a backlight used for light transmissive display devices, includes a plurality of light emitting elements such as light emitting diodes, and a lightguide plate configured to take in the light from the light emitting elements and to pass the light through its exit surface which is opposed to the display panel.
In such a light source device, some of the light emitting elements may be connected in series. In that case, if an error occurs in one of the light emitting elements and a circuit including the light emitting element with an error is shut down, other light emitting elements functioning normally are also turned off due to the shutdown of the circuit. On the exit surface of the lightguide plate, the brightness decreases not only in the area corresponding to the light emitting element with an error but also in the area corresponding to the light emitting elements turned off due to the error, and the visibility of the image on the display device will significantly deteriorate.